Researchers have found evidence that chronic fatigue syndrome (CFS) is a result of immunological dysfunction, meaning it is a biological illness and not a psychological disorder as commonly thought.

People with CFS experience extreme fatigue and difficulty concentrating due to headaches and muscle pain.

“We now have evidence confirming what millions of people with this disease already know, that CFS is not psychological,” stated researchers at Columbia University’s Center for Infection and Immunity in the United States.

The researchers identified distinct immune changes in patients diagnosed with chronic fatigue syndrome. They found specific patterns in patients who had the disease for three years or less, including increased amounts of immune molecules called cytokines, which were not present in controls or in patients who had the disease for more than three years.

The association was unusually strong with a cytokine called interferon gamma that has been linked to the fatigue that follows many viral infections.